1. Field of the Invention
This invention relates to hulls for watercraft. Particularly, this invention relates to configurable hull extensions to effectively widen the beam of watercraft and provide more planing area over a water surface.
2. Description of the Related Art
The hull is the watertight body of a watercraft, which supports the superstructure (or deckhouse) above it. The hull structure varies based upon the type of watercraft. Modern boats may comprise fiberglass or composite hulls where the structure may include supporting bulkheads, typical of traditional designs, or comprise a monocoque structure. For watercraft to be trailerable over roadways, hull size is limited by law. For example, many states may limit the maximum beam width to eight and a half feet to operate without a permit.
Hull shape design for watercraft has an ancient history. There are many variations depending upon the application of the particular watercraft. Hull shapes can range from simple box shapes, e.g. for barges, to sharp streamlined surfaces, e.g. for racing boats. Typically, a hull shape may either have smooth curves, such as an S-bottom, molded, round bilged or soft-chined hull, or have at least one knuckle (or discontinuity), such as a chined hull.
Hull types may be further categorized as being either displacement or planing, or something between (i.e. semi-displacement or semi-planing). A displacement hull is supported predominantly by buoyancy. Such hulls have limited speed and are often heavier than planing hulls. On the other hand, planing hulls are designed to develop positive dynamic lift such that the hull draft decreases with increasing speed. The dynamic lift reduces the wetted surface of the hull and therefore reduces the drag of the hull as it moves through the water. Planing hulls may be flat-bottomed, V-bottomed, or round bilged. Typically, a planing hull will have at least one chine.
Another category of watercraft employs hydrofoils, which operate to lift a watercraft hull out of the water and virtually eliminate hull drag. The hydrofoil acts as a wing as water passes across both the top and bottom surfaces of the hydrofoil. This is very different from a planing hull where water substantially passes only across the bottom surface. A successful hydrofoil watercraft is designed to transition between a wetted hull and an unwetted hull as the watercraft develops speed and is lifted out of the water. Typically, watercraft employing hydrofoils are very expensive to develop as the engineering is much more complex than traditional watercraft. Some prior work has been done to alter hull configurations in both traditional and hydrofoil watercraft described hereafter.
U.S. Pat. No. 6,895,883 issued May 24, 2005 to Coles describes a hydrofoil craft, particularly a method of economically modifying a conventional hull with cambered foils to obtain and calculate increased lift from dense spray and to achieve enhanced craft performance is disclosed. The present invention improves speed, fuel efficiency and rough water stability, reduced pitch and vertical accelerations. A catamaran or V-bottom hull is modified with chine mounted aerofoils, flexible dihedral cambered foils positioned beneath the water line and on either side of the bow so as to create turbulence in the forward end of a tunnel(s). Fixed forward tunnel cambered foil(s) and/or fixed or adjustable center tunnel cambered foils at the stern end of the tunnel to generate lift from pressure caused by dense spray in the tunnel(s) may also be provided.
U.S. Pat. No. 7,174,843 issued Feb. 13, 2007 to Tossavainen describes a hydrofoil unit for attaching to the stern of the hull of a boat. The unit includes a mount that mounts to the stern of the hull of the boat, a hydrofoil that is pivotally attached to the mount, a pivot assembly that pivotally attaches the hydrofoil to the mount, and apparatus for pivoting the hydrofoil relative to the mount. In one embodiment, the apparatus is automatic and includes an hydraulic cylinder that is pivotally attached to the transom of the boat and a strut that is pivotally attached to the hydraulic cylinder and the hydrofoil. In another embodiment, the apparatus is manual and includes an upper threaded rod that is pivotally attaching to the transom of the boat, a turnbuckle that is attached to the upper threaded rod, and a lower threaded rod that is attached to the turnbuckle and the hydrofoil.
U.S. Pat. No. 7,520,238 issued Apr. 21, 2009 to Patterson describes a vessel hull stabilization system is presented that uses hydrofoils mounted on the vessel. The hydrofoils create a counteracting force to the waves that would otherwise cause the vessel to roll and pitch. The hydrofoil is connected to the vessel in both passive and an active modes. The hydrofoil consists of a number of configurations that include a number of attached struts and foils which provide additional counteracting forces in response to wave action.
U.S. Pat. No. 8,051,793 issued Nov. 8, 2011 to Ulgen describes a marine vehicle with at least one hydrofoil at the lower hull of such marine vehicle, and at least one drive element for retracting a pair of hydrofoils mounted side-by-side on both sides of the symmetry axis of the hull of the marine vehicle. When hydrofoils are in the retracted position, the marine vehicle is converted to a conventional marine vehicle.
U.S. Pat. No. 8,122,840 issued Feb. 28, 2012 to Harber describes an improved displacement hull form for ships and boats, in one of many possible embodiments includes a transom stern hull form having a hull underside that is substantially horizontal in transverse orientation along the aft-most portion of said hull form, a pair of endplates having a substantially vertical orientation along the aft half of said hull form waterline length, a pair of cambered rudders located near the stern of said hull form with said cambered rudders having pressure faces oriented towards said hull form longitudinal centerplane, and stern buttock-line shaping defined by a supercavitating hydrofoil shape. The hydrodynamics of said hull form are improved in terms of reduced resistance, reduced trim and draft aft, and reduced ship wave train.
In view of the foregoing, there is a need in the art for apparatuses and methods to provide more planing area for watercraft over a water surface. There is a need for such apparatuses and methods without the complexity and cost of hydrofoils. There is also a need for such techniques to be configurable to particular applications. In addition, there is further need for such apparatuses to operate without exceeding trailerable vehicle requirements. These and other needs are met by the present invention as described in detail hereinafter.